Mid-Wisconsinan stratigraphy and paleoenvironments at the St. Charles Site in south-central Iowa; with Suppl. Data 91-04

R. G. Baker; D. P. Schwert; E A Bettis III; T. J. Kemmis; D. G. Horton; H. A. Semken

doi:10.1130/0016-7606(1991)103<0210:MWSAPA>2.3.CO;2

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Mid-Wisconsinan stratigraphy and paleoenvironments at the St. Charles Site in south-central Iowa; with Suppl. Data 91-04

Journal article

Peer reviewed

Mid-Wisconsinan stratigraphy and paleoenvironments at the St. Charles Site in south-central Iowa; with Suppl. Data 91-04

R. G. Baker, D. P. Schwert, E A Bettis III, T. J. Kemmis, D. G. Horton and H. A. Semken

Geological Society of America bulletin, Vol.103(2), pp.210-220

02/1991

DOI: 10.1130/0016-7606(1991)103<0210:MWSAPA>2.3.CO;2

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Abstract

A sequence of loess-mantled sediments exposed along Clanton Creek provides the first evidence of fluvial, pedologic, and biotic environments before the last glacial maximum in south-central Iowa. Two fining-upward fluvial sequences, one inset into the other, are exposed. Radiocarbon ages indicate that the alluvial fills are about 34,000 yr old.Basal gravel in the oldest fill contains well-preserved mammoth (Mammuthus) bones. Sparse seeds from this horizon suggest weedy flood-plain conditions. The younger alluvial fill contains well-preserved pollen, plant macrofossils, and insects. The pollen is dominated by nonarboreal taxa and Pinus, suggesting a prairie border or savanna environment. Vascular-plant and bryophyte macofossils indicate a variety of aquatic and marsh environments on the flood plain. Insects are mostly sympatric in mixed conifer and hardwood forest that extends along latitude 47 degrees to 49 degrees between eastern North Dakota and New England, but forest beetles are rare, and the fauna is dominated by openground forms. The site is interpreted as an open flood plain dotted with marshes and oxbow lakes; it was surrounded by open woodland or savanna similar to that in north-eastern North Dakota at present. July temperatures at the St. Charles site were probably 3 to 5 C degrees cooler than those at present.The pre-loess stratigraphy of the site differs markedly from that of upland sites and demonstrates that correlation between upland and lowland sequences cannot be done without adequate dating.

Paleoecology

Stratigraphy

United States

absolute age

alluvium

Arthropoda

Bryophyta

C-14

carbon

Cenozoic

Chordata

clastic sediments

dates

Elephantidae

Elephantoidea

Eutheria

fluvial environment

grain size

Insecta

Invertebrata

Iowa

isotopes

lacustrine environment

lithostratigraphy

loess

Madison County Iowa

Mammalia

Mammuthus

Mandibulata

microfossils

miospores

paleoclimatology

paleogeography

paleosols

paleotemperature

paludal environment

palynomorphs

Peoria Loess

Plantae

Pleistocene

pollen diagrams

Proboscidea

Quaternary

Quaternary geology

radioactive isotopes

riparian environment

Saint Charles Iowa

sediments

south-central Iowa

terrestrial environment

Tetrapoda

Theria

upper Pleistocene

Vertebrata

Wisconsinan

Details

Title: Subtitle: Mid-Wisconsinan stratigraphy and paleoenvironments at the St. Charles Site in south-central Iowa; with Suppl. Data 91-04
Creators: R. G. Baker - University of Iowa, Earth and Environmental Sciences
D. P. Schwert
E A Bettis III - University of Iowa, Earth and Environmental Sciences
T. J. Kemmis
D. G. Horton
H. A. Semken - University of Iowa, Earth and Environmental Sciences
Resource Type: Journal article
Publication Details: Geological Society of America bulletin, Vol.103(2), pp.210-220
Publisher: Geological Society of America (GSA)
DOI: 10.1130/0016-7606(1991)103<0210:MWSAPA>2.3.CO;2
ISSN: 0016-7606
eISSN: 1943-2674
Language: English
Date published: 02/1991
Academic Unit: Earth and Environmental Sciences
Record Identifier: 9983557558402771

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